Flash floods are more likely to occur in:

The correct answer is: a) River valleys.

Flash floods are more likely to occur in river valleys because they are naturally low-lying areas that are prone to flooding. When heavy rains fall, the water can quickly flow down the river valley, causing a flash flood.

Hilly areas are less likely to experience flash floods because the water has more time to spread out and dissipate. Plains are also less likely to experience flash floods because they are typically flat and do not have the same drainage systems as river valleys. Coastal regions are also less likely to experience flash floods because the water can flow out to sea.

Here are some additional details about each option:

• River valleys are naturally low-lying areas that are prone to flooding. When heavy rains fall, the water can quickly flow down the river valley, causing a flash flood.
• Hilly areas are less likely to experience flash floods because the water has more time to spread out and dissipate.
• Plains are also less likely to experience flash floods because they are typically flat and do not have the same drainage systems as river valleys.
• Coastal regions are also less likely to experience flash floods because the water can flow out to sea.